Lubricating oil compositions



United States Patent 3,232,882 LUBRICATING 02L COMPGSHTIQNS Glenn Fuller and Forrest J. Watson, Berkeley, Calif., as-

signors to Shell Gil Company, New York, N.Y., a corporation of New York No Drawing. Filed Mar. 28, 1962, Ser. No. 183,036 10 Claims. (Cl. 252--32.7)

This invention relates to oxidatively stabilized mineral lubricating oils and more particularly to mineral lubricating oil compositions which are stable under elevated temperatures and extreme pressure conditions.

It is known that certain sulfur-phosphorus containing compounds such as organic thiophosphate esters exhibit good extreme pressure promrties. However, oils containing such additives are non-resistant to oxidation processes even under mild conditions and attempts to inhibit oxidation of such oil compositions by means of Well known antoxidants such as alkyl phenols and aromatic amines have not been too successful. When such lubricating oil compositions are subjected to extreme conditions of temperature and pressure the situation becomes more aggravated.

It has now been discovered that mineral lubricating oils can be effectively stabilized over a wide temperature range and possess excellent extreme pressure and antiwear properties by incorporating in such oils minor amounts of each (0.01%2%, preferably 0.l%-1%) of two additives which are: (A) an oil-soluble pip-methylene bisphenol or monoether thereof represented by the formula XR (II) wherein R is an oil-soluble hydrocarbyl group, such as an alkyl, aryl, a-ralkyl, alkaryl or cycloalkyl radical having at least 6 and preferably a straight-chain alkyl radical having from 10 to 18 carbon atoms, the R s are the same or different groups selected from hydrogen, hydrocarbyl, or cationic group, such as metallic or non-metllic cationic group, such as mono or polyvalent metal (Ca, Ba, Cr, Mn, Fe, Cu, Ni, Cd) or amine, preferably an alkylamine, R is hydrogen or C alkyl radical, the Xs are independently chalcogen atoms having an atomic number of from 8 to 16, such as oxygen or sulfur and y is an integer of from 2 to 5, preferably 2.

The oil soluble bisphenol compound represented by formula (A) include: 1,l-bis(3,5-ditert-butyl-4-hydroxyphenyl) methane; 1 l-bis (3 ,5 -diisopropyl-4-hydroxyphenyl)methane; l,l-bis(3,5-di-sec-butyl 4 hydroxyphenyl) methane; -l,1-bis(3-isopropyl-5-tert butyl 4 hydnoxyphenyDrnethane; 1, l-bis 3 ,5 -di (2-oxtyl) -4-hydroxy-phenyl)methane; 1,l-bis(3-sec-butyl-5 (2 hexyl)4 hydroxyphenyDrnethane; 1, l-bis 3 -isopropyl-5-( 1,1,3 ,3 -tetrameth- .ylbutyl)4-hydroxyphenyl)methane; l,1-bis(3-tertbutyl-5- methyl-Z-hydroxyphenyl)methane; 1,1-bis(3-tert-butyl-5- .methyl-Z-hydroxyphenyl)ethane; 1,1 bis(3-tert-butyl-5- methyl-2-hydroxyphenyl)-propane; 1,l-bis(3-tert-butyl-5- methyl-Z-hydroxyphenyl)isobutane; 1,1-'bis( 3 methyl-5- tert-butyl-6-hydroxyphenyl)methane; 3,5,3',5-ditertbutyl- 4-methoxy-4'-cresol) and mixtures thereof.

3,232,882 Patented Feb. 1, 1966 ice The compounds represented by formula (B), namely the polysulfids of certain phosphorus compounds preferably can be represented by the following formulas:

A is an aliphatic amine, preferably a primary or secondary amine, such as C primary straight-chain amines, e.g., octylamine, laurylamine, etc., or branched-chain primary aliphatic amines, e.g., tC alkylamine, such as made by Rohm and Haas under the trade name Primene, e.g. Primene 8l-R and Primene JM-T or C secondary aliphatic amines, such as diamylamine, di-Z-ethylhexylamine, didecylamine, or mixtures thereof, or (A) can be represented as (A in (B and then it is a polyvalent metal such as alkaline earth metals, e.g. Ca, Ba, Sr or other polyvalent metals such as Zn, Pb, Sn, Fe or Cd.

The polysulfides of alkylphosphono compounds, e.g. 2,3- dithiaor 2,3,4-trithiaor 2,3,4,5-tetrathiaalkyl phosphonic compounds are prepared by reacting a mercaptide having at least 6 carbon atoms with a halomethanephosphono compound such as chlorornethanephosphonic acid or a dialkyl chloromethanephosphonate or their thio-derivatives in the presence of elemental sulfur and a suitable solvent, such as an aqueous alcoholic solution, at reflux temperature and under inert conditions until the reaction is completed which normally requires from 1 to about 5 days. The mercaptans include aliphatic mercaptans, such as hexyl, octyl, decyl, dodecyl, octadecyl mercaptans, cycloalkyl mercaptans, such as cyclohexyl mercaptan, dicyclohexyl mercaptan, aralkyl mercaptan, such as phenyldecyl mercaptan, benzyl mercaptan and the like. Instead of the mercaptans, the mercaptides can be used such as the alkali metal (Na or K) mercaptides of the above compounds. Suitable halomethanephosphonic compounds include chloromethanephosphonic acid, mono or dihydrocarbyl chloromethanephosphonates, e.g., mono or dibutyl chloromethanephosphonate, mono or di-Z-ethylhexyl chloromethanephosphonate, mono or dilauryl chloromethanephosphonate, mono or diphenyl chloromethanephosphonate, mono or dicyclohexyl chloromethanephosphonate, mono or dibenzyl chloromethanephosphonate, di-

. butyl chloromethanedithiophosphonate, diphenyl chloromethanedithiophosphonate, dibutyl chloro1nethanedithiophosphonate, alkali metal salts such as Na and K salts of chlorornethanephosphonic acid, Na and K salts of monobutyl chloromethanephosphonic acid, Na and K salts of monodecyl chloromethanephosphonic acid and the like.

A preferred method of making the 2,3-dithia or 2,3,4- trithia or 2,3,4,5-tetrathiaalkylphosphonates is to react a mixture of a suitable mercapto compound, such as an alkali metal (Na or K) C1043 alkyl mercaptide, elemental sulfur and a chloromethanephosphonic acid, its ester or salt, e.g., an alkali metal (Na or K) salt of chloromethylphosphonic acid in an alcoholic solution under reflux conditions and under an inert atmosphere to form the alkylpolythiomethylphosphono compound, e.g. the alkali metal salt of dithiaalkylphosphonic acid. The salt, for example, is then treated with a strong acid such as hydrochloric acid to spring the free dithiaalkylphosphonic acid, which can be converted into desired partial or full esters or polyvalent metal salts or amine salts for use as oil, fuel and grease additives as well as other uses. If the partial or full ester is the desired end product, then instead of starting with the salt of chloromethylphosphonic acid the ester can be used such as the mono or dialkyl ester of chloromethylphosphonic acid.

The following examples illustrate the preparation of additives for use in accordance with the present invention.

EXAMPLE I.DIBUTYL 2,3-DITHIATRI- DECYLPI-IOSPHONATE About 174 grams of n-decyl mercaptan was charged into a flask containing about 73 grams of KOI-I (85%) and 900 ml of ethanol. To the mixture 32 grams of elemental sulfur was added and the mixture refluxed until homogeneous at which time about 242.5 grams of dibutyl monochloromethylphosphonate was added and the mixture refluxed for about 24 hours. The reaction was cooled and the precipitant was separated by water dilution and extracted by repeated ether washing and thereafter dried over MgSo and the solvent was vacuum stripped. The end product dibutyl 2,3-dithiatridecylphosphonate was a straw yellow liquid readily soluble in mineral oil and exhibited good EP propertites.

EXAMPLE II.MONOBUTYL 2,3-DITI-IIATRI- DECYLPHOSPHONATE About 206 grams of the product of Example I was charged into a flask containing aqueous solution of KOH in ethanol and the mixture was refluxed for 48 hours. The reaction product was acidified with dilute HCl and extracted with ether, washed and dried as in Example I, and the recovered product was monobutyl 2,3-dithiatridecylphosphonate, an oil-soluble product having good EP properties.

EXAMPLE III.-2,3-DITI-IIATRIDECYL- PHOSPHONIC ACID Stoichiometric amounts of the potassium salt of decyl mercaptan, elemental sulfur and the potassium salt of monochloromethylphosphonic acid were dispersed in an aqueous solution of ethanol and the mixture was refluxed at 78 C. under a nitrogen atmosphere for about 1 day. The potassium 2,3-dithiatridecylphosphonate was then treated with strong hydrochloric acid to spring the acid product which was recovered by extraction with ether. The final product was 2,3-dithiatridecylphosphonic acid.

EXAMPLE -IV.-3-PHENYL 2,3-DITHIA- PROPYLPHOSPHONIC ACID The procedure of Example II is followed except that potassium salt of phenylmercaptan is used instead of potassium salt of decylmercaptan and the final product is 3-phenyl 2,3-dithiapropylphosphonic acid.

EXAMPLE V.-PRIMENE JM-T (t-C H NH to t-C ,H.,NH MONOBUTYL 2,3-DITHIATRIDEC- YLPHOSPHATE Primene JMT salt of monobutyl 2,3-dithiatridecylphosphonate is prepared by reacting the product of Ex- 4: ample II with Prirnene IMT in the amount sufficient to completely neutraiize both acid groups, at about 50 C. in an alcoholic solution and thereafter recovering the amine salt from the alcoholic solution.

The following additional compounds may be prepared: 2,3-dithiaundecylphosphonic acid, 2,3,4-trithiahexadecylphosphonic acid, ornega-cyclohexyl-2,3-dithiapropylphosphonic acid, omega-phenyl 2,3 dithiabutylphosphonic acid, omega-phenyl-2,3,4-trithiabutylphosphonic acid, dibutyl 2,3,4-trithiatetradecylphosphonate, omega-phenyl- 2,3-dithiatridecyl acid phosphonate, dibutyl-2,3 dithiapentadecyldithiaphosphonate, dibutyl phenyl-2,3 dithiamethylphosphonate, dithiaoctylcyclohexyl 2,3,4 trithiamethylthiophosphonate, dioctyl amine dodecylmercaptomethylphosphonate, dioctadecylamine omega-phenyl-2,3- dithiabutylphosphonate, tert-octadecylamine 2,3- dithiapentadecylphosphonate, iron salt of 2,3-dithiatridecylphosphonic acid and mixtures thereof.

The particularly preferred additive mixtures illustrative of the present invention in mineral lubricating oil in concentrations indicated include:

(A) Example I (0.015% P) and bis(3,5-ditert-butyl-4- hydroxyphenyDmethane 0.2%

(B) Example II (0.5% P) and bis(3,5 -ditert-butyl-4- hydroxyphenyl)methane (0.5

(C) Example III (0.02% P) and bis(3-isopropyl-5-tertbutyl-4-hydroxyphenyl)methane (0.3

(D) Example 1V (0.01% P) and bis(3,5-ditert-butyl-4- hydroxyphenyl)methane (0.2%

(E) Example I (0.02% P) and bis(3,5-ditert-butyl-4- hydroxyphenyl)methane (0.5%

(F) Example IV (0.12% P) and methyl ether of bis(3,5

ditert-butyl-4-hydroxyphenyl)methane.

(G) Example V (0.015% P) and bis(3-methyl-5-tertbutyl-4-hydroxyphenyl)methane (0.2%

(I-I) Example I (0.015% P) and bis(3,5-isopropyl-4-hydroxyphenyl)methane (0.05%

(1) Example V (0.05% P) and bis(3,5-amyl-4-hydroxyphenyl)methane (0.01%

(I) Mixture of Examples I and V (50/50) (0.03% P) and bis(3,5-ditert-butyl 4 hydroxyphenyl)methane (0.5

The mineral lubricating oils may be derived from a variety of petroleum base stocks and are preferably paraffinic and/ or naphthenic in character; they may also contain substantial proportions of hydrocarbons having aromatic character. The viscosity may vary within wide limits so that the oils may belong, for example, to SAE classes 5W, 10W, 20W, 20, 30, 4-0, 50, 60 or 70. Suitable oils may be derived from highly parafiinic crudes in which case distillation and/ or dewaxing may be sufficient to provide a suitable base stock; chemical or selective solvent treatment may be used if desired, but is preferably kept to a minimum for economic reasons. Mixed-base crudes and even highly aromatic crudes which contain paraflinic hydrocarbons also provide suitable oil base stocks after refining by well-known techniques such as the separation of distillate fractions of suitable boiling range followed by solvent extraction with selective solvents, for example, furfural or phenol, to provide raffinate fractions, dewaxing, and chemical treatment, for example sulfuric acid treatment.

In addition to functioning as synergistic antioxidants, the additive mixtures of the present invention have been found to be extremely valuable in reducing wear and inhibiting corrosion.

In order to demonstrate the unexpected results which are obtained by use of the additive mixtures of the present invention, the Dornt oxidation test described in Industrial and Engineering Chemistry, August 1942, vol. 34, page 927 was used for evaluation, the conditions being C. With Fe catalyst present, and the results are shown in Table I.

5 Table 1 Base: Mineral white oil Conditions: 150 C. Fe catalyst Induction Additive Composition: period, hrs. Composition A (present invention) 122.5

Composition G (present invention) 174 Composition 1 [zinc dioctyl dithiophosphate (0.015% P)+bis(3,5-ditert-buty1 4 hydroxyphenyl)methane (0.5 41.5 Composition [tricresylphosphate (0.2% P)+ bis( 3,5 ditert-butyl-4-hydroxypehuyl)methane (0.2%)] 11 Composition 3: bis(3,5-ditert-butyl 4 hydroxyphenoDmethane (0.5%) 15.5 Composition 4: Example I (0.015% P) 63 Composition 5: zinc dioctyl dithiophosphate Compositions of this invention are useful for providing stability and other desired properties to petroleum products such as mineral lubricating oils which also contain small amounts (0.1% to 3%) of other agents such as the following: detergents such as metal organic sulfonates, e.g. neutral or basic Ca, Ba, or Zn petroleum sulfonates or non-ash forming detergents such as Acryloids of the 300 and 900 series, e.g. Acryloid 917, 966 or 315X which are copolymers of vinyl pyrrolidone and lauryl methacrylate of varying molecular weight such as of from 200,000 and 1,000,000 and described in Canadian Patent 592,974 or copolymers of vinyl pyridine and alkyl methacrylate as described in US. Patents 2,839,512, 2,889,282, 2,915,471 and 2,944,974; viscosity index improvers and pour point depressants such as the oil-soluble polymethacrylates available under the name Acryloid 150, 618, 710 and 768, described in US. Patent 2,710,842; condensation products of chlorinated paraflin Wax and naphthalene; extreme pressure agents such as aliphatic amine salts of monochloromethanephosphonic acid or trichloromethanephosphonic acid, or the ester or amide of such acids; organic sulfides and mixtures thereof.

We claim as our invention:

1. A mineral lubricating oil composition comprising a major amount of mineral lubricating oil and minor amounts each sufiicient to stabilize and impart extreme pressure properties to the mineral lubricating oil of an oil-soluble compound having the general formula CR1 010-18 aJkyl-SSCH2 0R1 wherein the Rfs are selected independently from the group consisting of hydrogen, C alkyl radical and an alkylamine and an oil-soluble alkylated methylene bisphenol.

2. The composition of claim 1 wherein the R are C alkyl radicals and the alkylated methylene bisphenol is bis(3,5-ditert-butyl-4-hydroxyphenyl)methane.

3. The composition of claim 1 wherein one of the R s is hydrogen and the other is a C alkyl radical, and the alkylated methylene bisphenol is bis(3,5-ditert-butyl- 4-hydroxyphenyl)methane.

4. The composition of claim 1 wherein one of the R s is a C alkyl radical and the other is an alkylamine and the alkylated methylene bisphenol is bis(3,5-ditert-butyl- 4-hydroxyphenyl)methane.

5. Amineral lubricating oil composition comprising a major amount of mineral lubricating oil and minor amounts each sufiicient to impart stability and extreme pressure properties to the oil of a C1048 alkyl 2,3-dithiarnethylphosphonic acid and bis(3,5-ditert-butyl-4- hydroxyphenyl)methane.

6. A mineral lubricating oil composition comprising a major amount of mineral lubricating oil and minor amounts sufiicient to impart stability and extreme pressure properties to the oil of an ester of C1048 alkyl 2,3- dithiamethylphosphonic acid and an alkanol having from 1 to 4 carbon atoms and bis(3,5-ditert-butyl-4-hydroxyphenyl) methane.

7. A mineral lubricating oil composition comprising a major amount of mineral lubricating oil and minor amounts suflicient to impart stability and extreme pressure properties to the oil of an alkylamine salt of C alkyl 2,3-dithiamethylphosphonic acid and bis(3,5-ditertbutyl-4-hydroxyphenyl)methane.

8. A mineral lubricating oil composition comprising a major amount of mineral lubricating oil and minor amounts each suflicient to impart stability and extreme pressure properties to the oil of 2,3-dithiatridecylphosphonic acid and bis(3,5-ditert-butyl-4-hydroxyphenyl) methane.

9. A mineral lubricating oil composition comprising a major amount of mineral lubricating oil and minor amounts each suflicient to impart stability and extreme pressure properties to the oil of an ester of 2,3-dithiatridecylphosphonic acid and an alkanol having from 1 to 4 carbon atoms and bis(3,5-ditert=buty1-4-hydroxyphenyl) methane.

10. A mineral lubricating oil composition comprising a major amount of mineral lubricating oil and minor amounts each sufficient to impart stability and extreme pressure properties to the oil of salt of 2,3-dithiatridecylphosphonic acid and bis(3,5-di tert-butyl-4-hydroxyphenyl)methane.

References Cited by the Examiner UNITED STATES PATENTS 2,807,653 9/1957 Filbey et a1. 252-52 X 2,857,305 10/1958 Birum 25246.6 X 3,041,279 6/1962 Calhoun et al. 252-466 X I DANIEL E. WYMAN, Primary Examiner. 

1. A MINERAL LUBRICATING OIL COMPOSITION COMPRISING A MAJOR AMOUNT OF MINERAL LUBRICATING OIL AND MINOR AMOUNT EACH SUFFICIENT TO STABLIZE AND IMPART EXTREME PRESSURE PROPERTIES TO THE MINERAL LUBRICATING OIL OF AN OIL-SOLUBLE COMPOUND HAVING THE GENERAL FORMULA 